#!/bin/sh
set -e

### BEGIN INIT INFO
# Provides:           docker
# Required-Start:     $syslog $remote_fs
# Required-Stop:      $syslog $remote_fs
# Should-Start:       cgroupfs-mount cgroup-lite
# Should-Stop:        cgroupfs-mount cgroup-lite
# Default-Start:      2 3 4 5
# Default-Stop:       0 1 6
# Short-Description:  Create lightweight, portable, self-sufficient containers.
# Description:
#  Docker is an open-source project to easily create lightweight, portable,
#  self-sufficient containers from any application. The same container that a
#  developer builds and tests on a laptop can run at scale, in production, on
#  VMs, bare metal, OpenStack clusters, public clouds and more.
### END INIT INFO

export PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin:/usr/local/bin

BASE=docker

# modify these in /etc/default/$BASE (/etc/default/docker)
DOCKERD=/usr/bin/dockerd
# This is the pid file managed by docker itself
DOCKER_PIDFILE=/var/run/$BASE.pid
# This is the pid file created/managed by start-stop-daemon
DOCKER_SSD_PIDFILE=/var/run/$BASE-ssd.pid
DOCKER_LOGFILE=/var/log/$BASE.log
DOCKER_OPTS=
DOCKER_DESC="Docker"

# Get lsb functions
. /lib/lsb/init-functions

if [ -f /etc/default/$BASE ]; then
    . /etc/default/$BASE
fi

# Check docker is present
if [ ! -x $DOCKERD ]; then
    log_failure_msg "$DOCKERD not present or not executable"
    exit 1
fi

check_init() {
    # see also init_is_upstart in /lib/lsb/init-functions (which isn't available in Ubuntu 12.04, or we'd use it directly)
    if [ -x /sbin/initctl ] && /sbin/initctl version 2>/dev/null | grep -q upstart; then
        log_failure_msg "$DOCKER_DESC is managed via upstart, try using service $BASE $1"
        exit 1
    fi
}

fail_unless_root() {
    if [ "$(id -u)" != '0' ]; then
        log_failure_msg "$DOCKER_DESC must be run as root"
        exit 1
    fi
}

cgroupfs_mount() {
    # see also https://github.com/tianon/cgroupfs-mount/blob/master/cgroupfs-mount
    if grep -v '^#' /etc/fstab | grep -q cgroup \
        || [ ! -e /proc/cgroups ] \
        || [ ! -d /sys/fs/cgroup ]; then
        return
    fi
    if ! mountpoint -q /sys/fs/cgroup; then
        mount -t tmpfs -o uid=0,gid=0,mode=0755 cgroup /sys/fs/cgroup
    fi
    (
        cd /sys/fs/cgroup
        for sys in $(awk '!/^#/ { if ($4 == 1) print $1 }' /proc/cgroups); do
            mkdir -p $sys
            if ! mountpoint -q $sys; then
                if ! mount -n -t cgroup -o $sys cgroup $sys; then
                    rmdir $sys || true
                fi
            fi
        done
    )
}

case "$1" in
    start)
        check_init
        
        fail_unless_root

        cgroupfs_mount

        touch "$DOCKER_LOGFILE"
        chgrp docker "$DOCKER_LOGFILE"

        ulimit -n 1048576

        # Having non-zero limits causes performance problems due to accounting overhead
        # in the kernel. We recommend using cgroups to do container-local accounting.
        if [ "$BASH" ]; then
            ulimit -u unlimited
        else
            ulimit -p unlimited
        fi

        log_begin_msg "Starting $DOCKER_DESC: $BASE"
        start-stop-daemon --start --background \
            --no-close \
            --exec "$DOCKERD" \
            --pidfile "$DOCKER_SSD_PIDFILE" \
            --make-pidfile \
            -- \
                -p "$DOCKER_PIDFILE" \
                $DOCKER_OPTS \
                    >> "$DOCKER_LOGFILE" 2>&1
        log_end_msg $?
        ;;

    stop)
        check_init
        fail_unless_root
        if [ -f "$DOCKER_SSD_PIDFILE" ]; then
            log_begin_msg "Stopping $DOCKER_DESC: $BASE"
            start-stop-daemon --stop --pidfile "$DOCKER_SSD_PIDFILE" --retry 10
            log_end_msg $?
        else
            log_warning_msg "Docker already stopped - file $DOCKER_SSD_PIDFILE not found."
        fi
        ;;

    restart)
        check_init
        fail_unless_root
        docker_pid=`cat "$DOCKER_SSD_PIDFILE" 2>/dev/null`
        [ -n "$docker_pid" ] \
            && ps -p $docker_pid > /dev/null 2>&1 \
            && $0 stop
        $0 start
        ;;

    force-reload)
        check_init
        fail_unless_root
        $0 restart
        ;;

    status)
        check_init
        status_of_proc -p "$DOCKER_SSD_PIDFILE" "$DOCKERD" "$DOCKER_DESC"
        ;;

    *)
        echo "Usage: service docker {start|stop|restart|status}"
        exit 1
        ;;
esac
